Background: Parents of children with intellectual and neurodevelopmental disorders are a highly burdened group that faces additional challenges during the COVID-19 pandemic. Methods: In this study, parents of children with intellectual and neurodevelopmental disorders (N = 600) living in Canada participated in a cross-sectional online survey. Results: More than 96% of the parents reported facing additional challenges due to the pandemic. COVID-19-related stressors correlated with poorer mental and physical health. Parents who reported a higher amount of COVID-19-related stressors also reported more post-traumatic stress disorder (PTSD) symptoms. Discussion: Resuming and implementing new services for children with intellectual and neurodevelopmental disorders and their parents will be key in alleviating the challenges for those parents.